System for controlling movements of a load lifting device

ABSTRACT

The invention relates to a system for controlling movements of a load lifting device on a horizontal plane whereby the load lifting device ( 6 ) comprises a vertically oriented carrier element ( 14 ). The vertical orientation of said carrier element is at least due to gravity when the element is in a resting position. At least one motor device ( 23   a,    23   b,    23   c ) is connected in order to execute said movements. Said movements can be controlled by a force impinging in a substantially horizontal direction relative to the carrier element ( 14 ), in particular a force which can be applied and which can be detected by a sensor device ( 25 ). In order to improve upon a control system in a simple to operate and low cost manner, in particular in such a way that load independent control is achieved with a high degree of positioning accuracy and rapid positioning speed, the sensor device ( 25 ), according to the invention, is embodied in such a manner and arranged in such a manner with respect to the carrier element ( 14 ) that the force is detected in a path-free manner. Path-free in this context is taken to mean that components of the sensor device ( 25 ) do not move through macroscopically registerable path with respect to each other.

The invention under consideration refers to a system for controlling aload-lifting device, in particular, a crane traveling crab, conducted ona track construction, with regard to its movements in a horizontalplane, wherein the load-lifting device has a carrying element that atleast in its position at rest and influenced by gravity, is verticallyoriented, with the load-lifting device being correlated with at leastone motor drive device to carry out the movements, which can becontrolled as a function of the force that acts on the carrying elementin an essentially horizontal direction and is applied, in particular,manually, and can be recorded with a sensor device.

In particular, the invention refers to such a system, in which theload-lifting device has a flexible carrying element that can swing andbe wound, and which is oriented vertically in its position at rest andaffected by gravity.

Crane runways with a traveling crab (one-track runway), which moves backand forth in only one coordinate direction, and also with a travelingcrab (traveling crane), which moves over an area in two coordinatedirections, are known. The traveling crab itself is conducted on onetrack; this track is then perhaps conducted on other tracks with onemovement direction, vertical to its longitudinal extension. Theload-lifting device or traveling crab has a flexible carrying element,which can be wound in many cases, for example in a carrier cable or achain, which in its state at rest and affected by gravity is orientedvertically. Moreover, rigid, rod-like carrying elements are also oftenused. With the load-lifting device, a load can be raised or lowered in avertical spatial direction, in that the carrying element is wound orunwound or, as a whole, is moved vertically.

In many such crane runways, the traveling crab is conducted, movingfreely, over corresponding, free-running bearings, for example, rollers.Here, the horizontal movements of the traveling crab must be induced bythe operator manually via the carrying element, in that the travelingcrab is pulled or pushed in the corresponding direction with thecarrying element or the load hanging on it. In the case of a flexiblecarrying element, great deflections of the carrying element may berequired, depending on the height of the load, before the traveling crabmoves at all. At the end of the individual movement, there is often alsoan undesired excess swiveling—that is, unwanted further movements of thetraveling crab beyond the desired position, and perhaps relatively hard,against an end stop of the pertinent carrying track. Therefore, it isoften necessary for the traveling crab or the carrying element to alsobe braked and perhaps even pulled back somewhat, once more. In thisrespect, a relatively wide, reverse deflection of the carrying elementis then necessary. From all this, a poor, cumbersome, time- andeffort-consuming operation results.

Crane runways with motor-driven traveling crabs are also known. Usually,the traveling crab drive is controlled from a driver's cabin or a manualkeyboard via corresponding, for example, electrical, switches. Problemsarise hereby. Above all, swinging movements of the load hanging on thecarrying element result from each change of speed—that is, from eachacceleration and braking operation. In unfavorable cases, such swingingor oscillation movements can be so strong that, for example, afree-standing crane can even tip over.

In order to create a system for controlling a load-lifting device, inparticular, a system for controlling the movement of a crane travelingcrab, which is conducted on a track construction and has a verticallyoriented carrying element that, in a control-technical simple manner,ensures a particularly comfortable operation with a simultaneously highdegree of safety, the German Utility Model, West German Patent No. 29712 462 U1, teaches the correlation of the load-lifting device to carryout the movements and at least one motor drive device that can becontrolled as a function of a force that acts on the carrying element inan essentially horizontal direction. This force, which is to be appliedmanually, in particular, is recorded by means of a sensor device in theknown system. Thus, the operator now needs only to apply a slightmanipulation force directly on the load or in the area of the loadholding device, wherein the lifting device moves with the load in thecorresponding direction, automatically, by means of the motor. Withoutthe effect of force, the load comes to a standstill immediately. Theload can therefore be very sensitively and precisely manipulated andplaced.

The pertinent force can be recorded in the known system directly, forexample, by means of DMS technology (DMS=wire strain gauge), which ispossible, above all, when using a rigid carrying element, wherein theindividual manipulation force can be transferred via the rigid carryingelement, almost without deflections, to a sensor device, located in thearea of the load-lifting device.

Alternately and as is well known, an indirect force recording isprovided, above all, when using a carrying element that is flexible andtherefore can swing, in that deflections of the carrying element, whichare independent of the individual manipulation force and that are forcedwith respect to the vertical, are recorded. To this end, a sensor deviceis provided, with which deflections of the carrying element, relative tothe vertical, are recorded, and which then produce signals to controlthe drive device of the load-lifting device, as a function of thedirection and preferably also the degree of deflection. The sensordevice of the known system has a measuring unit that, on the one hand,consists of a deflection element, connected with the carrying element,and on the other hand at least one distance sensor. The distance sensoris held, horizontally, next to the deflection element, at a certaindistance, which can change by means of the manipulation force. Thus, apath-dependent force recording is available. One disadvantage of thisknown system is in that the operating forces are dependent on theload—that is, with bigger loads, for example, with loads above 100 kg, ahigher manipulation force must be applied than with smaller loads, so asto deflect the carrying element with respect to the vertical by one andthe same amount.

The goal of the invention under consideration is to improve a controlsystem of the aforementioned type, in a simple and low-cost manner, withrespect to its operating comfort, particularly in such a way that, aload-independent control can take place with a high positioning accuracyand a rapid positioning speed.

This is attained, in accordance with the invention, in that the sensordevice is designed in such a way, and is situated with reference to thecarrying element, so that the force is recorded path-free. “Path-free”is thereby understood to mean that the parts of the sensor device,relative to one another, do not traverse any macroscopically recordablepaths.

Wire strain gauge-force recorders, magnetoelastic force recorders,piezoelectric force recorders, or fiber-optical force recorders can beadvantageously used as path-free force recorders, in accordance with theinvention.

For an advantageous operation, the sensor device can be designed, withrespect to the production of control signals, in such a way that amovement of the load-lifting device in a certain coordinate direction isbrought about by the force of the carrying element, approximately in thesame direction and essentially corresponding to the desired movementdirection. The sensor device can be sensitively designed in such a waythat even a very small force, such as that which appears with an onlyvery slight deflection of a flexible carrying element in a maximum anglerange of only approximately 0 to 3°, with respect to the vertical,triggers a motor drive in the corresponding direction. The drive speedcan be controlled as a function of the amount of force (lower speed withsmaller force and greater speed with stronger force).

When using a flexible carrying element, such as a cable, the tension ofthe carrying element (cable tension) increases with an increasing load,which has an advantageous influence on the effect of the carryingelement on the path-free force recorder, which it is next to. So thatthe system responds, large deflection angles of the carrying element,with respect to the vertical, are not necessary.

Here, it is particularly advantageous if the manipulation force is notconverted into speed according to a linear curve, but rather accordingto a progressive curve. In this way, a slow start and a soft braking areattained and swings during starting and braking are avoided.

Even with a relatively large load, a relatively small, essentiallyhorizontally acting manipulation force, which can thus be appliedmanually by one operator, very simply and without a special forceeffort, is advantageously sufficient. Also, a position-exact stop isreadily possible since upon reaching the desired position, the motordrive immediately comes to a standstill by merely letting go, becausethe manipulation force becomes zero.

The invention under consideration is suitable for a one-axle model ofcrane runways, but preferably for two-axle crane runways. With thetwo-axle model, it is possible, in accordance with the invention, tocontrol two drives, correlated with the two coordinate directions in oneplane (X, Y), individually or simultaneously, so that by overlapping thedrives all arbitrary movements in directions inclined with respect tothe coordinate axes are possible, in that the carrying element is alsoacted on with force or is precisely deflected in the individual, desireddirection of movement.

Moreover, a boom, which is held so that it can swivel around a verticalaxis in a certain angle range, can be correlated with a motor drivedevice, which can be steered as a function of the force that acts on thecarrying element in an essentially horizontal direction, and that can beapplied manually and recorded by means of a sensor device.

On the basis of a very smooth mode of operation attained by theinvention, this system is suitable in particular for use in combinationwith so-called weight balances. The load-lifting device is therebydesigned in such a way that the practically “suspended” load, which ishanging on the carrying element, can be raised or lowered by a slightforce, which is manually applied in a vertical direction. By combinationwith the invention under consideration, it is thus possible tomanipulate the suspended load, independent of its weight, by very slightforces and arbitrarily in space—that is, it can be moved verticallyand/or horizontally. Such a combined embodiment can therefore bedesignated as a “three-coordinate balancer” or a “space balancer.”

Other advantageous development features of the invention are containedin the subclaims and the following description.

The invention will now be more precisely explained with the aid ofpreferred exemplified embodiments, which are illustrated in thedrawings. The figures show the following:

FIG. 1, a simplified perspective representation of a crane runway with aload-lifting device (traveling crab), which moves along a horizontalmovement axis X—X;

FIG. 2, a crane runway in a model with a load-lifting device, whichmoves in the direction of two coordinate axes X—X and Y—Y over ahorizontal area;

FIG. 3, an enlarged side view in the arrow direction III, according toFIG. 2, with an additional representation of a load and an operator;

FIG. 4, a vertical section through the main component of a sensor deviceof the control system;

FIG. 5, a horizontal section in plane V—V, according to FIG. 4;

FIG. 6, a force/speed diagram for a preferred embodiment with aprogressive conversion of force into speed;

FIG. 7, analogous to FIG. 4, a vertical section through the maincomponent of a first model of the sensor device of a control system inaccordance with the invention.

FIG. 8, analogous to FIG. 5, a horizontal section in plane VIII—VIII, inaccordance with FIG. 7;

FIG. 9, a lateral section through a first model of a boom of a controlsystem, in accordance with the invention, which can rotate around atleast one vertical axis;

FIG. 10, a top view of the boom shown in FIG. 9;

FIG. 11, a lateral section through a second model of a boom of a controlsystem, in accordance with the invention, which can rotate around atleast one vertical axis;

FIG. 12, a top view of the boom shown in FIG. 11;

FIG. 13, analogous to FIG. 7, a vertical section through the maincomponent of a second model of the sensor device of a control system, inaccordance with the invention;

FIG. 14, a lateral section through a third model of a boom of a sensorsystem, in accordance with the invention, which can rotate around atleast one vertical axis;

FIG. 15, a top view of the boom shown in FIG. 14;

FIG. 16, a lateral section through a fourth model of a boom of a controlsystem, in accordance with the invention, which can rotate around atleast one vertical axis;

FIG. 17, a lateral section through a fifth model of a boom of a controlsystem, in accordance with the invention, which can rotate around atleast one vertical axis.

In the various drawings, the same parts are always provided with thesame reference symbols, so that they are described only once, as a rule.

FIG. 1 first shows, by way of example, a crane runway 1 in a model of aone-track runway. Here, a track construction 2 is provided with a track4, which extends horizontally and particularly in a straight line, onwhich a load-lifting device 6, particularly a so-called traveling crab8, is conducted back and forth in the direction of a horizontalcoordinate axis X—X. The track construction 2 is affixed via a holdingelement 10 on a building roof and/or special stationary carrier 12 (seeFIG. 2), which is not depicted.

In the first exemplified embodiments, described in the following, theload-lifting device 6 has a flexible carrying element 14, which can berolled and thus accordingly swung and which is shown here, by way ofexample, as a carrier cable (steel cable), but it can also be formed,for example, from a chain. On its one lower end, the carrying element 14has a load-holding device 16—in the simplest case, for example, a hookor the like; it can also be a suction device, a gripping device, palletforks, and the like. At the other end, a motor winding and unwindingdevice 18 is connected with the carrying element 14 (see FIG. 4). Thus,the load-holding device 16 with a load 20 (FIG. 3) can be moved in avertical spatial direction Z—Z—that is, it can be raised or lowered—viathe carrying element 14.

FIG. 2 shows the crane runway 1, by way of example, in a second model,as a traveling crane. The track construction 2 thereby consists of, onthe one hand, the track 4, guiding the load-lifting device 6 in thecoordinate direction X—X, and on the other hand other tracks 22, wherebythese other tracks 22 are fixed stationary over the holding element 10,and wherein the track 4 is conducted so that it moves back and forth ina second horizontal coordinate direction Y—Y, on tracks 22. The twocoordinate directions X—X and Y—Y are situated vertically with respectto one another and form a plane X-Y. Thus, the load-lifting device 6 canbe arbitrarily moved over the entire area covered by the trackconstruction 2.

The load-lifting device 6 is correlated with at least one motor drivedevice 23 a for its movements in the direction X—X and/or Y—Y (FIG. 1).In the preferred embodiment according to FIG. 2, a corresponding drivedevice 23 a and 23 b is provided for the two movement directions X—X andY-Y1; this, however, is only schematically (in block representation)shown in the figures—including the corresponding acting connections (inthe form of undesignated arrows). To steer each drive device 23 a, 23 b,a special control system is provided in these exemplified embodiments,wherein each drive device 23 a, 23 b can be steered as a function of adeflection of the carrying element 14, which is forced, proceeding fromthe vertical alignment into the position at rest, influenced by gravityand automatically adjusted. To this end, the system has a special sensordevice 24—reference is made, in particular, to FIGS. 4 and 5.Deflections of the carrying element 14, relative to the vertical 26 canbe very sensitively recorded with this sensor device 24. The sensordevice 24 then produces signals to control the individual drive device23 a, 3 b of the load-lifting device 6, as a function of the directionand preferably also the degree (angle measurement). With respect to theproduction of the control signals, the sensor device 24 is preferablydesigned in such a way that a movement of the load-lifting device 6 isbrought about in a certain coordinate direction—for example, ±X and/or±Y, by a deflection of the carrying element 14, which is approximatelyin the same direction and essentially corresponds to the desiredmovement direction.

This is illustrated in FIG. 3, by way of example, with the aid of thedepicted arrows. If, for example, the operator 28 manually acts on thecarrying element 14 by means of the load 20 and/or the load-holdingdevice 16 in the direction of the arrow 30, with a manipulation force Fand in this way, corresponding to the direction of movement −Y, deflectsinto a slightly inclined orientation 32 via an angle α from the vertical26, then the control signals produced by the sensor device 24 have aneffect on the drive of the load-lifting device 6, precisely in thedirection of movement −Y, that is, in the direction of the arrow 34.Correspondingly, a reverse force F or deflection shown by the arrow ofmovement 36 would have an effect on a drive in the direction of thearrow 38, that is, in the direction of movement +Y. Something similar isalso valid for the movement axis X—X and also for movements in bothaxes, that is, for overlapped movements, inclined with respect to thecoordinate axes.

In accordance with FIGS. 4 and 5, the sensor device 24 has a measurementunit 40 with a housing 41. In the (comparison) example shown, in whichan indirect force recording is provided via a force-proportionaldeflection of the carrying element 14, the measurement unit 40 has, onthe one hand, a deflection body 42, connected with the carrying element14, and on the other hand at least one distance sensor 44 a, 44 b,correlated with the individual coordinate axes X—X or Y—Y, and thus withthe corresponding drive device 23 a, 23 b. The deflection body 42 sitson the carrying element 14 so that it can move longitudinally in such away that, on the one hand, the carrying element 14 can move in thedirection of the vertical axis Z—Z, relative to the deflection body 42,which is essentially held stationary in this axis direction, for thepurpose of raising or lowering the load or the load-holding device 16;on the other hand, the deflection body 42 is moved along, withdeflections of the carrying element 14, relative to the distance sensors44 a, 44 b, to change the distance, which can be recorded for thecreation of the control signals. Each distance sensor 44 a, 44 b is, inthis respect, held horizontal, at a certain distance, next to thedeflection body 42.

For the model having the possibility of movement of the load-liftingdevice 6 in two coordinate directions X and Y, the measurement unit 40has—as shown—two distance sensors 44 a, 44 b situated, in accordancewith the two coordinate axes, at an angle of 90° with respect to oneanother. The deflection body 42 is appropriately designed as acircular-cylindrical body and is located in a hollow-cylindrical holdinghousing 41, wherein the sensors 44 a, 44 b are held within the walls ofthis holding housing 41. The deflection body 42 is, in this way,surrounded by a uniform annular gap 46, in its position at rest(carrying element 14, oriented exactly vertical). The inside diameter ofthis annular gap 46 is recorded, with measurement technology, by thesensors 44 a, 44 b, then converted into control signals. To this end,the distance sensors 44 a, 44 b are connected with an only schematicallyshown electronic evaluation unit 47, which in turn creates the controlsignals for the drive devices 23 a, 3 b, with the aid of the pertinentinitial sensor signals.

In accordance with FIG. 4, the measurement unit 40 has a stationaryguide 48 for the carrying element 14 in the upper area of the holdinghousing 41, in order to support the carrying element 14, laterally, withrespect to deflections. The guide 48 can be formed by a lead-in opening,which has such an opening cross section, adapted to the cross section ofthe carrying element 14, that the carrying element 14, which movesrelative to the vertical axis, is conducted in a stationary manner, inthis fixed point, relative to the horizontal axis. This fixed point thusforms swinging axes for the deflections of the section of the carryingelement 14, which lies (hangs) beneath.

Each drive device 23 a, 23 b is preferably designed as aspeed-controlled motor, in particular with a traveling mechanism actingon the carrying track construction 2. It can advantageously be, forexample, a wheel and disk drive. Of course, alternatively, gearwheeldrives or synchronous belt drives can also be provided.

As can be deduced from the diagram in FIG. 6, the manipulation force For the deflection of the carrying element resulting therefrom ispreferably converted into the drive speed v, in accordance with aprogressive curve 50. This is attained with a corresponding design orprogramming of the electronic evaluation unit 47, which makes possiblean adaptation of the curve and thus the response behavior of the systemto different load-lifting tasks. The advantages of this progressivecurve 50 with a flat initial rise include, above all, a soft,extensively jerk-free starting and stopping of the load-lifting device 6and the avoidance of swings during starting and braking, whereinnevertheless even high speeds are possible. If, on the other hand, theconversion took place with the aid of a linear curve 52, indicated witha broken line in FIG. 6, then a jerky start/braking, which producesswings back and forth, would result from this. A correspondingly flatrise of a linear curve would have, above all, the disadvantage that evenwith a high force F, only a relatively low speed could be produced,which would then lead to the system not reacting with slight (short)deflections.

The system is preferably used in combination with a so-called weightbalancer. Preferably, the carrying element 14 is thereby correlated witha torque-controlled drive (not shown in the drawing), for its verticalmovements in the axis direction Z—Z, which, depending on the load,produces a constant torque in such a way that the load 20 is heldstatically in the vertical direction in any position—that is, itpractically hovers. Slight, manually applied forces (load changes),acting vertically upwards or downwards, automatically bring about araising or a lowering of the load 20 because of the constant torque.This results in a very simple and smooth manipulation of the supposedlyhovering load in space by very slight forces, even in the verticaldirection.

A model of a system for controlling a load-lifting device 6, inaccordance with the invention, is first shown, by way of example, inFIGS. 7 and 8. Instead of the sensor 24 described above, which is basedon the measurement of a certain distance, a sensor device 25 isprovided, which is designed and situated, relative to the carryingelement 14, in such a way that the force F, which is applied for thecontrol of the system, in particular a force F that strikes in the areaof a load-holding device 16, located on the free, lower end of thecarrying element 14, is recorded path-free.

As in the previously shown example, the sensor device 25 has, in turn, ameasurement unit, which is designated here with the reference symbol 39.The measurement unit 39 consists of a housing 41, in which, however,there is no deflection body 42 here, but rather a measurement body 43,connected with the carrying element 14, and at least one force recorder45 a, 45 b, 45 c, 45 d (in the model shown, two), correlated with theindividual coordinate axis X—X, Y—Y or the pertinent drive device 23 a,23 b. Each of the force recorders 45 a, 45 b, 45 c, 45 d is thereby inpermanent contact with the measurement body 43. The carrying element 14is, in turn, a flexible carrying element, such as a cable, which can bewound and which runs over three guide rollers 43 a, 43 b, 43 c of themeasurement body 43. The measurement body 43 is located, stationary, inthe direction of the vertical axis Z—Z, and for the purpose of raisingor lowering a load 20, the carrying element 14 can be moved through acentric opening in the measurement body 43 is formed by the guiderollers 43 a, 43 b, 43 c, which are staggered by 120° with respect toone another, and can move longitudinally in the direction of thevertical axis Z—Z, relative to the measurement body 43.

The additional details of the mode of operation of the sensor device 25(for example, the response of the sensor device 25 with a deflection ofthe carrying element 14, relative to the vertical axis 26, the magnitudeand direction of the signals produced in the control device 47 for thedrive devices 23 a, 23 b, the type of drive devices 23 a, 23 b used, thepossibility of the construction of the load-lifting device 6 as a weightbalancer, nonlinear curve, etc.) agree with the models of the controlsystem described in the preceding. For that reason, measurement device40 and measurement device 39 are indicated as alternatives in the blockrepresentation of FIG. 1. However, due to the fact that the forcerecorder 45 a, 45 b, 45 c, 45 d of the measurement device 39, inaccordance with the invention, is essentially located right next to themeasurement body 43, without any gaps, a load-dependent manipulationforce for the production of a control signal is not needed, on the onehand, and the system ensures a constantly high functional reliability,even under more adverse environmental conditions, on the other hand. Thepath-free force recording thus ensures an increased reliability of thesystem, in that there is a lower soiling risk for the sensor device 25and thus less of a possibility for the long-term negative influence onthe sensitivity than when the force recorder(s) 44 a, 44 b is/are held,next to a deflection body 42, at a certain distance (annular gap 46).

As a path-less force recorder 45 a, 45 b, 45 c, 45 d, the sensor device25 can advantageously have at least one wire strain gauge-forcerecorder. Wire strain gauge (DMS)-force recorders are the most importantrepresentatives of the electrical force recorders. In the simplest case,four wire strain (DMS) gauges are cemented on an elastic hollow cylinderto produce such a wire strain (DMS) gauge-recorder. If the cylinder iscompressed by a load, the resistances of the DMS are changed. The fourDMS are interconnected in a Wheatstone bridge. Instead of a tube-shaped(hollow-cylindrical) deformation body, rod-like deformation bodies canalso be used. What is particularly advantageous is that DMS-forcerecorders are suitable for static and dynamic measurements and fornominal forces in the range of 5 N to 20 MN.

Furthermore, as force recorders 45 a, 45 b, 45 c, 45 d, the sensordevice 25 can have at least one magnetoelastic force recorder. The modeof action of such a magnetoelastic force recorder is based on themagnetoelastic effect of ferromagnetic materials, wherein theirpermeability changes with the effect of a certain force. The resultinginductance change of a coil with a core made of the ferromagneticmaterial, on which the force acts, directly changes the current thatflows through the coil. Since the current can be measured directly, nomeasurement reinforcers are required; this, in particular, predestinessuch force recorders for use under robust operating conditions.

As path-less force recorders 45 a, 45 b, 45 c, 45 d, piezoelectric forcerecorders can also be advantageously used in the sensor device 25. Thebasis for these piezoelectric force recorders is the piezoelectriceffect, according to which charges appear on certain crystals if theyare mechanically stressed. Quartz crystals have the most consistentcharacteristics and the best insulation, making them most suitable formeasurement purposes. In a piezoelectric force recorder (pressuregauge), the force mechanically acts on two piezoelectric crystalelements, which lie behind one another, but they are electricallyparallel. In this way, the required insulation of a middle metalelectrode, situated between the two piezoelectric crystal elements withrespect to a metal housing and serving as the second electrode, can beattained, without further expense, only by means of the twopiezoelectric crystal elements. The initial (signal) magnitude of apiezoelectric force recorder is a charge, which is converted into acorresponding voltage by a charge reinforcer. The advantage of usingthis force recorder is revealed mainly with quick dynamic measurements,in which the important aspects are the small structural size and theinsensitivity toward temperature fluctuations. Piezoelectric forcerecorders also have a very good resolution and low measurementunreliability.

Finally, there is also the possibility that, as force recorders 45 a, 45b, 45 c, 45 d, the sensor device 25 has at least one fiber-optical forcerecorder. With such a recorder, either the recording or the transmissionof the measurement value takes place by means of a fiber opticalwaveguide. Depending on the function of the fibers, one distinguishesbetween intrinsic and extrinsic fiber-optical recorders. In an intrinsicfiber-optical recorder, the fibers themselves are used as the sensitiveelement, in that the conversion of the measurement value (force F) intoan optical signal takes place. For example, with a lateral force effecton an optical fiber, wrapped with a thin wire, a loss of theconducted-through light current arises, which can be recorded byevaluation electronics via photodetectors. In an extrinsic,fiber-optical sensor, the primary purpose is the transmission of themeasurement value from the measurement site to an evaluation site, in asdisturbance free a manner as possible. The conversion of the measurementvariable into an optical signal takes place at the measurement site,outside the fiber—for example, by means of integrated-optical ormicrooptical components. Thus, the force to be measured can control theopening width of a diaphragm for a light current, whereas another partof the light current remains unchanged, as a reference signal. Theevaluation electronics then compares the two light currents andproduces, therefrom, a force indication in a path-neutral manner. Theuse of fiber-optical recorders is particularly suitable ifmeasurement-technologically “difficult” environmental conditionsprevail, for example, strong electrical or magnetic disturbance fields,high temperatures, or explosive or corrosive atmospheres.

Two advantageous embodiments of the invention are shown in FIGS. 9 and10, as well as 11 and 12. For the two embodiments, it is characteristicthat the system for controlling the load-lifting device in accordancewith the invention has a boom 54, which is supported so that it canswivel around a vertical axis W—W (FIGS. 9 and 11), around an angle φ(FIGS. 10 and 12).

As schematically indicated in FIGS. 10 and 12, the boom 54 can becorrelated with a motor drive device 23 c, which, however, is notnecessarily required and which can be controlled as a function of aforce F that acts on the carrying element 14 in an essentiallyhorizontal direction and that is applied manually and can be recorded bymeans of the sensor device 25. Also, a drive device 23 c can, as withother drive devices 23 a, 23 b, be advantageously designed as aservomotor, in particular with a wheel and disk drive, gearwheel drive,or synchronous belt drive.

The sensor device 25 can thereby be advantageously designed in such away that a movement of the load-lifting device 6 in the direction ofdeflection by the angle φ (arrow with the reference symbol 56) isbrought about by a force F, which is applied approximately in the samedesired direction of movement.

Also, the drive speed v of the drive device 23 c can in turn becontrolled—as shown above—as a function of the magnitude of theindividually applied force F—advantageously, with the aid of aprogressive curve 50 with a flat initial rise, as FIG. 6 shows.

As a result of the fact that the measurement unit 39 has four path-freesensors 45 a, 45 b, 45 c, 45 d, which are situated in accordance withthe two coordinate axes X—X, Y—Y, at an angle of 90° with respect to oneanother, control signals can be produced both for the linear drivedevices 23 a, 23 b as well as for the drive device 23 c to swivel theboom 54 in the electronic evaluation unit 47, simultaneously with theaid of the individual initial sensor signals, depending on the effectdirection of the applied force F in the four quadrants formed by thecoordinate axes X—X, Y—Y.

Here, it is of particular advantage if the housing 41 of the measurementdevice 39 can rotate with respect to the measurement body 43, with themeasurement body 43 and the housing 41 being affixed to the boom 54 insuch a way that when the boom 54 is swiveled by the angle φ around thevertical axis W—W, the housing 41 is rotated by the same angle in such away that the housing 41 retains its angle orientation with the path-lessforce recorders 45 a, 45 b, 45 c, 45 d, relative to the trackconstruction 2.

This conformal movement of the housing 41 means that with each angle φby which the boom 54 is swiveled, a simple signal evaluation by theelectronic evaluation unit 47 is possible, since the pair of forcerecorders 45 a, 45 b, and 45 c, 45 d are always oriented at the sameangle, with respect to the horizontal main axes X—X, Y—Y of thespace—for example, as is particularly clear from FIGS. 10 and 12, on theone hand parallel to the axis, and on the other hand at right angles tothe axes X—X, Y—Y.

For the movement of the housing 41, a coupling rod 58 (FIGS. 9 and 10)that is articulated so that it can rotate at one end on the boom 54 andon the other end on the housing 41, or also a corresponding synchronousbelt drive 60 (FIGS. 11 and 12), a chain drive, or the like, can beused. Such a synchronous belt drive 60 can, moreover, also be deducedfrom the enlarged representation in FIG. 7. It runs parallel to the boom54 above the sensor device 25, whose housing 41 has an axial,tube-shaped extension 62 in the direction of the boom 54, which isencompassed by the synchronous belt drive 60 and is held, by means ofrolling bearings 64, on a likewise tube-shaped projection piece 66 onthe free end of the boom 54. The carrying element 14 is guided throughthe inside of the projection piece 66 over a deflection roller 68.

In the embodiments of a system for controlling a load-lifting device 6in accordance with the invention and shown in FIGS. 13 to 17, theholding element 14 is not designed as a cable, but rather rigidly formedas a rod, in contrast to the models described in the preceding.Moreover, the basic structure of the measurement unit 39 is essentiallythe same as the model described above. To this extent, reference is madeto the pertinent explanations above. Differences with the above model,however, still exist in the support of the rigid holding element 14 andin a special design of the operating grip 70.

The holding element 14 is not conducted over guide rollers 43 a, 43 b,43 c, but rather preferably has—as shown—two spherical thickenings 14 a,14 b are used for its support in the measurement body 43 and in the boom54.

The operating grip 70, designed in the shape of a tube, encompasses theholding element 14 and has two sleeve-like metal parts 70 a, 70 b,insulated from one another, as can also be clearly seen from FIGS. 14,16, and 17. The metal parts 70 a, 70 b are electrically bypassed by themanual grip of the operator 28, wherein a current circuit is closed,turning off a safety blocking that is switched on when the system is atrest.

The operating grip 70 is, moreover, also especially designed for thecontrol of vertical movements of loads 20 hanging on the carryingelement 14. A load 20 can be raised or lowered by small forces appliedmanually in the vertical direction 26. The recording of the force takesplace thereby with a sensor 72, by means of which a distance change of asliding sleeve 74, brought about by a vertical operating force, isdetected, with a corresponding signal being emitted to the electroniccontrol unit 47. As occurs in an analogous manner with the signals ofthe path-free sensors 45 a, 45 b, 45 c, 45 d, this signal can beconverted there into a control signal for a drive device for thevertical movement of the load 20. Such drive devices are shown in FIGS.14, 15, and 17 with the reference symbol 23 d. FIGS. 13, 16, and 16contain, by way of example, in the form of action arrows, anillustration of the described signal flow from the grip 70, especiallyfrom its sensor 72 to the electronic control unit 47, wherein FIG. 14,by way of example, in the form of an action arrow, also contains theillustration of the signal flow from the electronic control unit 47 tothe vertical drive 23 d. As was already mentioned, with such acombination with the invention under consideration, it is thus possibleto manipulate the suspended load 20, independent of its weight, by verysmall forces arbitrarily in space—that is, it can be moved verticallyand/or horizontally. In the representation shown in FIG. 13 (moreover,in FIGS. 14 and 16 also), a hook is provided as a load-holding device16, which is found directly below the operating grip 70.

Another nondepicted execution possibility for the measurement device 39consists of directly placing the sensor device 25, for the detection ofthe control forces F for the horizontal movement, in the operating grip70. Preferably, four path-free sensors 45 a, 45 b, 45 c, 45 d can bedesigned for the quadrant-exact recording of the forces F by wire straingauges.

In two different views, FIGS. 14 and 15 show, in turn, a control systemin accordance with the invention—with a third model of the rotatableboom 54 and with the second model of the measurement unit 39. Therepresentations in the drawing are selected analogous to those of thefirst model (FIGS. 9 and 10) and of the second model (FIGS. 11 and 12).The most substantial difference of the third model, compared to thevariants described in the preceding, is that the boom 54 consists of twoarms 54 a, 54 b, connected with one another in an articulated manner. Asshown in FIGS. 10 and 12, with the boom 54, the first arm 54 a can beswiveled around the vertical axis W—W at an angle φ1 between arm 54 aand the X—X axis; the second arm 54 b can be swiveled around a verticalaxis W1—W1 at an angle φ1 between arm 54 b and arm 54 a. As in the firsttwo models, when swiveling the two boom arms 54 a, 54 b, a subsequentmechanical movement of the sensor device 25 takes place in such a waythat the path-less force recorders 45 a, 45 b, 45 c, 45 d retain theirangle orientation, relative to the track construction 2 or to the axesof the X-Y plane. In particular, a synchronous belt drive 60 is providedfor the subsequent mechanical movement, as with the second model of theboom 54, wherein, here, two synchronous belt drives 60 a, 60 b—one foreach arm 54 a, 54 b of the boom 54—are used.

The boom 54 is conducted in a manner such that it can move vertically,on a rod 76, which is connected in a stationary manner with thetraveling crab 8, wherein for a movement in the Z—Z direction, a specialdrive 23 d can be provided, which, as already mentioned, can becontrolled and—for example, similar to the representation in FIG. 4 forthe carrying element 14, which is flexible there—can be connected with amotor winding and unwinding device 18 for a cable 78. (All existingdrive devices 23 a, 23 b, and 23 d are not only shown schematically butalso representationally in FIGS. 14 and 15, as well as also in the otherfigures. Special drives 23 c for the angle adjustment of the boom 54 orits arms 54 a, 54 b are not provided, since this adjustment is donemanually.)

In the model of a control system in accordance with the invention, shownin FIG. 16, the boom 54 (in a fourth model) is also formed from two arms54 a, 54 b. The vertical mobility of the load 20, however, is attainedhere in that the first arm 54 a can swivel not only around the verticalaxis W—W in a horizontal direction, but also in a vertical direction.For this purpose, the arm 54 a consists of two swivel levers 80 a, 80 bthat are located parallel to one another, and which are articulated sothey can move by rotating on one end with a holding part 82 connectedwith the traveling crab 8, and on the other end with a holding part 84connected with the second arm 54 b.

In contrast to the previously shown models of the system of theinvention, it is not a mechanical but rather an electrical subsequentmovement of the measurement device 39 or sensor device 25, following themovement of the boom 54 in the X-Y plane, which is implemented and whichcan be designated as “subsequent movement via an electrical shaft.”Incremental swing-angle measurement disks (encoder) 86,88 are providedin the individual hinge points as devices for the creation of signalsfor the angles Ψ, Ψ₁ around which the boom arms 54 a, 54 b are swiveled;these measurement disks are coaxially arranged with respect to the swingaxes W—W, W1—W1 of the boom arms 54 a, 54 b, which run vertically. Thesignals corresponding to the swing angles Ψ, Ψ₁ of the arms 54 a, 54 bare conducted to the electronic evaluation unit 47 where, by addition orsubtraction, a resulting angle value is calculated for an actuator 23 efor the subsequent movement of the path-less sensors 45 a, 45 b, 45 c,45 d. This actuator 23 e is preferably a stepping motor. The subsequentmovement can take place advantageously, for example, via a synchronousbelt drive 60, acting on the measurement unit 39, but also actingdirectly from the actuator 23 e to the measurement unit 39.

The rotating hinges of the arms 54 a, 54 b on the vertical axes W—W,W1—W1 or the swivel levers 80 a,80 b on the horizontal axes (which arenot designated more specifically) can be advantageously braked with thecontrol of the traveling mechanisms 23 a, 23 b, so that while moving, anundesired spontaneous movement does not appear due to the inertia ofmasses of the aforementioned parts.

The activation of the blocking brakes, found on the rotating hinges,which bring about a rigid relative position of the arms 54 a, 54 b, or80 a, 80 b can be advantageously implemented via the operating grip70—particularly in that the operator 28, by manual grip, electricallybypasses the two sleeve-like metal parts 70 a, 70 b, insulated from oneanother as described above, wherein a corresponding activation circuitis closed. This is moreover possible with all exemplified embodiments,in which rotating hinges are provided.

Another model of a control system in accordance with the invention, witha boom 54, which can rotate on a vertical axis W—W, is shown in FIG. 17.This model has several features in common with the model shown in FIGS.14 and 15, but the boom 54, which moves by rotating, is articulated viathe axis W—W, directly on the traveling crab 8 and does not move byrotating on the vertical rod 76. Another vertical rod 76 is alsopresent, on which, however, the load-holding device 16—in this case afork—is vertically conducted. The vertical guiding and control of theload-holding device 16 occurs in the same way as with the model shown inFIGS. 14 and 15, via a vertical drive 23 d, acting on a winding device18 for a cable 78, which can be controlled, in turn, by the electronicevaluation unit 47. This receives its control signals, in turn, from themeasurement device 39 with the path-less operating sensors 45 a, 45 b,45 c, 45 d and for the operating grip 70, in which a sensor 72 for thevertical control is located. The operating grip 70 and the measurementdevice 39 also form one unit here, as with the models described in thepreceding; however, this unit is affixed, in this case, to the verticalrod 76, which is articulated on the traveling crab 8 so that it moves byrotating. For this model also, a subsequent mechanical movement of thesensors 45 a, 45 b, 45 c, 45 d or a subsequent movement in accordancewith the type of electrical shaft can be provided.

The invention is not limited to the exemplified models shown, but ratheralso includes all models that work in a similar manner in the sense ofthe invention. This concerns, in particular, the sensor device 25; here,any other embodiment with which forces can be recorded path-less on thecarrying element 14 and which can be converted into control signals isalso suitable. The provided drives 23 a, 23 b, 23 c can be designed aselectrical, pneumatic, and/or hydraulic motors. The electronicevaluation unit 47, shown only schematically in the examples, canpreferably be integrated in a moveable part of the system, such as thetraveling crab 8.

In addition, the specialist can amplify the control system, inaccordance with the invention, with suitable technical measurements.With regard to such possibilities for the control of vertical movementsof the load 20, reference is also made to the preceding models, in theirfull extent, particularly with respect to the object of German UtilityModel Application DE 299 02 364.8.

Furthermore, the invention is not limited to the combination of featuresdefined in claim 1, but rather can also be defined by any othercombination of specific features of all individual features disclosed asa whole. Basically, this means that practically any individual featureof claim 1 can be left out or can be replaced by at least one individualfeature, disclosed somewhere else in the application. In this respect,claim 1 is to be understood merely as a first formulation attempt forthe invention.

REFERENCE SYMBOLS

-   1 Crane runway-   2 Track construction-   4 Track-   6 Load-lifting device-   8 Traveling crab-   10 Holding elements-   12 Carrier-   14 Carrier element-   14 a Thickening on 14-   14 b Thickening on 14-   16 Load-holding device-   18 Unwinding device-   20 Load-   22 Track-   23 a Drive device (X—X)-   23 b Drive device (Y—Y)-   23 c Drive device for 54 (rotation in X-Y plane)-   23 d Drive device (Z—Z)-   23 e Drive device for 25 or 39-   24 Sensor device-   25 Sensor device-   26 Vertical-   28 Operator-   30 Force effect direction-   32 Orientation of 14 (deflected)-   34 Movement direction of 14 at 30-   36 Force-effect direction-   38 Movement direction of 14 at 36-   39 Measurement unit of 24-   40 Measurement unit of 24-   41 Housing of 39, 40-   42 Deflection body of 40-   43 Measurement body of 39-   43 a Guide roller in 43 for 14-   43 b Guide roller in 43 for 14-   43 c Guide roller in 43 for 14-   44 a Distance sensor in 40-   44 b Distance sensor in 40-   45 a Path-free sensor in 39-   45 b Path-free sensor in 39-   45 c Path-free sensor in 39-   45 d Path-free sensor in 39-   46 Annular gap around 42-   47 Electronic evaluation unit-   48 Guide of 40-   50 Curve v of F-   52 Curve v of F-   54 Boom-   54 a First boom arm-   54 b Second boom arm-   56 Movement direction of 54-   58 Coupling rod-   60 Synchronous belt drive-   60 a First synchronous belt drive of 60-   60 b Second synchronous belt drive of 60-   62 Extension of 41-   64 Rolling bearings-   70 Projection piece on 54-   70 a Deflection roller for 14-   70 Operating grip-   70 a First metal part of 70-   70 b Second metal part of 70-   72 Sensor in 70-   74 Sliding sleeve-   76 Rod-   78 Cable-   80 a Swivel lever of 54 a-   80 b Swivel lever of 54 a-   82 Holding part for 80 a, 80 b on 8-   84 Holding part for 80 a, 80 b on 54 b-   86 Encoder (Axis W—W)-   88 Encoder (Axis W1—W1)-   F Force-   v Speed-   W—W Swivel axis of 54 or 54 a-   W1—W1 Swivel axis for 54 b-   X Spatial coordinates-   X—X Spatial direction (horizontal)-   X-Y Spatial plane (horizontal)-   Y Spatial coordinate-   Y—Y Spatial direction (horizontal)-   Z Spatial coordinate-   Z—Z Spatial direction (vertical)-   a Deflection angle of 14-   j Swivel angle of 54 or 54 a-   j1 Swivel angle of 54 b

1. A load-lifting apparatus with a control system for movements in ahorizontal plane defined by coordinate axes (X-Y), comprising: aload-lifting device having a carrying element oriented vertically (Z—Z)at least when in a position at rest and influenced by gravity; a motordrive operatively associated with the carrying element to impartmovement to the load lifting device in a substantially horizontaldirection on at least one axis as a function of force (F) appliedmanually to the carrying element in a substantially horizontaldirection; a sensor device operatively associated with the motor driveand responsive to the manually applied force; the sensor device having ahousing with a measuring body in contact with the carrying element, and;the sensor device having at least one force transducer allocated to arespective coordinate axis of the motor drive and in contact with themeasuring body so as to detect path-free a horizontal movement impartedto the measuring body by the force manually applied to the carryingelement, whereby the motor drive imparts the substantially horizontalmovement to the load lifting device in response to the force manuallyapplied to the carrying element.
 2. System according to claim 1,characterized in that the carrying element is a flexible carryingelement that can swing back and forth and can be wound, and which isoriented vertically (Z—Z) in its position at rest and influenced bygravity.
 3. System according to claim 1, characterized by a supportedboom operative to swivel around at least one vertical axis, by an angle.4. System according to claim 3, characterized in that the boom comprisesa first arm operative to swivel around a first vertical axis by a firstangle, and a second arm operative to swivel around a second verticalaxis, by a second angle.
 5. System according to claim 3, characterizedin that the boom is correlated with a motor drive device that can becontrolled as a function of a force that acts on the carrying element ina substantially horizontal direction and can be recorded by means of thesensor device.
 6. System according to claim 1, characterized in that thesensor device detects a force (F) that acts on the carrying element inthe area of a load-holding device, which is located on a free lower endof the carrying element.
 7. System according to claim 1, characterizedin that the sensor device produces signals that can be detected in anelectronic evaluation unit as a function of the direction, and also as afunction of the magnitude of the force (F); with the electronicevaluation unit producing signals for controlling the motor drive of theload-lifting device.
 8. System according to claim 1, characterized inthat the sensor device is operative to cause a movement of theload-lifting device in a certain direction within a certain coordinatedirection in response to a force, which is applied in the same movementdirection.
 9. System according to claim 1, characterized in that thedrive speed of the motor drive is controlled as a function of themagnitude of the applied force.
 10. The system as in claim 9, whereinthe magnitude of increase in the drive speed becomes progressivelygreater in direct proportion to the magnitude of the applied force, sothat an initial relatively low magnitude of increase in the drive speedin response to an initial increment of applied force becomes greater inresponse to the same increment in force applied at a relatively greatermagnitude of the applied force.
 11. System according to claim 1,characterized in that the load-lifting device (6) is operative to movein the direction of two coordinate axes, which are perpendicular withrespect to one another, wherein each axis is correlated with a separatemotor drive device of the motor drive and with both drive devices beingcontrolled by the sensor device.
 12. System according to claim 1,characterized in that the force (F) is detected by a direct forcetransmission to the sensor device in response to manually produced,force-dependent deflections of the carrying element, which are imposedwith respect to a vertical axis.
 13. System according to claim 1,characterized in that the sensor device has a measurement unit with thehousing and with the measurement body, which is connected with thecarrying element via guide rollers, and at least one force detectorwhich is correlated with respective coordinate axes (X—X; Y—Y) or withthe respective at least one motor drive device, and which is in contactwith the measurement body.
 14. System according to claim 13,characterized in that the measurement body is situated in a stationarymanner in the direction of a vertical axis, and that for the purpose ofraising or lowering a load, the carrying element can move through acentric opening, via the guide rollers, in the measurement body, bysliding longitudinally in the direction of the vertical axis, relativeto the measurement body.
 15. System according to claim 13, characterizedin that the measurement unit has four force detectors that are locatedin accordance with the two coordinate axes (X—X; Y—Y) that are at anangle of 90°, with respect to one another.
 16. System according to claim13, characterized in that the housing of the measurement device isoperative to turn with respect to the measurement body, with themeasurement body and the housing being affixed to the boom or an arm ofthe boom in such a way that when the boom or the at least one arm of theboom is swiveled by at least one angle around at least one correspondingvertical the housing is turned by the same angle or by a summary angle,in such a way that the housing with the force recorders retains itsangle orientation, relative to a track construction on which theload-lifting apparatus is disposed.
 17. System according to claim 16,characterized in that a coupling rod (58), articulated on one end to theboom and on the other end to the housing is provided so as to turn thehousing.
 18. System according to claim 16, characterized in that aflexible drive element is provided to turn the housing.
 19. Systemaccording to claim 16, characterized in that a motor drive is providedto turn the housing.
 20. System according to claim 19, characterized inthat the motor drive is operative to turn the housing via an electronicevaluation unit.
 21. System according to claim 20, characterized in thatfor the production of signals for the angle, so as to swivel the boom orthe at least one boom arm, an incremental rotating angle measurementelement is provided, located coaxially with respect to the correspondingvertical axis of the boom or the at least one arm of the boom, whereinthe at least one measurement element produces signals corresponding toat least one swivel angle and conducted to the electronic evaluationunit, where an angle is calculated for the motor drive for thesubsequent movement of the force recorders.
 22. System according toclaim 1, characterized in that as a force detector, the sensor devicehas at least one wire strain gauge-force transducer, one magnetoelastictransducer, one piezoelectric transducer, or one fiber-optical forcetransducer.
 23. System according to claim 1, characterized in that theload-lifting device (6) is designed as a weight balancer.
 24. Systemaccording to claim 1, characterized in that the carrying element iscorrelated with a torque-controlled drive for the vertical movements(Z—Z), which produces, as a function of the load, a constant torque, andthat the load is held statically in any position in a vertical direction(Z—Z), with small forces applied manually and acting substantiallyvertically, bringing about a raising or lowering of the load.
 25. Systemaccording to claim 1, characterized in that the sensor device forms astructural unit with an operating grip, and in that the sensor device isintegrated into the operating grip.
 26. The system as in claim 1,wherein the load-lifting device comprises a crane-traveling crabdisposed on track elements with respect to the horizontal plane. 27.System according to claim 26, characterized in that an electronicevaluation unit is integrated in a moveable part of the system in thecrane-traveling crab.